Module 4: Somatosensory Pathways Flashcards
Somatosensory
Refers to the sensations of touch, pain, temperature, vibration, and proprioception
Posterior column-medial lemniscal pathway conveys which somatosensory abilities?
proprioception
vibration sense
fine, discriminative touch
Proprioception
awareness of the position of one’s limb/joint
Anterolateral/ventrolateral pathways include which tracts?
spinothalamic and associated tracts
The anterolateral/ventrolateral pathways are responsible for which somatosensory abilities?
pain
temperature sense
crude touch
T or F: Since some aspects of touch sensation are carried by both pathways, touch sensation is not eliminated completely in isolated lesions to either pathway.
T
4 types of sensory neuron fibers
A-alpha (13-20µm)
A-beta (6-12µm)
A-gamma (1-5µm)
unmyelinated C’s (0.2-1.5µm)
What sensory modalities are conducted most quickly?
proprioception (A-alpha & A-beta)
superficial touch (A-beta)
deep touch (A-beta)
vibrations (A-beta)
What sensory modalities are conducted most slowly?
pain (A-gamma) cool temperature (A-gamma) pain (C) warm temperature (C) itch (C)
What do the A-alpha’s conduct?
proprioception
What do the A-beta’s conduct?
proprioception
superficial touch
deep touch
vibrations
What do the A-gamma’s conduct?
pain
temperature (cool)
What do the unmyelinated C’s conduct?
pain
temperature (warm)
itch
Where are sensory neuron cell bodies located?
dorsal root ganglia
What are the functions of each of the bifurcated dorsal root ganglion stem cell axons?
A) convey sensory information from the periphery
B) carry information to the spinal cord through the dorsal nerve roots
dermatome
A peripheral region innervated by sensory fibers from a single nerve root level
Sensation for the face is provided by which cranial nerve?
CN V, trigeminal nerve
Sensations for most of the head (excluding the face) are provided by nerve roots at what level?
C2
What are the two main somatosensory pathways?
posterior column-medial lemniscal pathway.
